1. Field of the Invention
The present invention relates to a data transmission equipment capable of autonomously and selectively transmitting data received at arbitrary time intervals to any of a plurality of parallel transfer paths.
2. Description of the Related Art
In processing equipment, such as an electronic computer, a plurality of processing units are communicatively coupled by digital signals, for performing data processing. In general, contents of data processing thus performed in a distributed manner are varied with the processing units, while data required for such processing and results obtained in the respective processing units are different from each other. When interconnection is performed for each data processing required for data transfer by an input/output port in order to couple such a plurality of processing units, hardware is extremely complicated and the size and the cost of the entire apparatus increases.
The inventors have proposed a data transmission unit which can transmit different types of data groups through the same data transmission path in Japanese Patent Laying-Open Gazette No. 174857/1987.
FIG. 1 is a block diagram schematically showing the data transmission unit proposed by the inventors.
Referring to FIG. 1, a brief description is made for the data transmission unit, which branches data to two transmission paths for transmitting the data. Each of the data transmission paths 1, 7 and 8 illustrated in FIG. 1 is formed by a data register for transmitting data and a transfer control part. An identifier transmission path 2 is provided in parallel with the data transmission path 1. The identifier transmission path 2 is adapted to transmit an identifier called a tag. This identifier indicates whether the data received on the data transmission path 1 is to be transmitted to the data transmission path 7 or the other path 8.
When both of the data transmission paths 7 and 8 are empty to enable data transmission, subsequent data transmission paths (not shown) supply UK signals 5a and 6a to control parts 5 and 6 respectively. Similarly, UL signals 5d and 6d from preceding stages of the data transmission paths 7 and 8 are also supplied to the control parts 5 and 6 respectively. The UL signals 5d and 6d are supplied from arbitrary data transmission paths which precede the data transmission paths 7 and 8, for indicating that the data transmission paths are empty for enabling data transmission. Upon input of the UK signal 5a, the UL signal 5d, the UK signal 6a and the UL signal 6d, the control parts 5 and 6 judge whether the data transmission path 7, the path preceding the data transmission path 7, the data transmission path 8 and the patch preceding the data transmission path 7 are empty respectively, to transmit data, which may be theretofore held, to subsequent stages, and enter active states for enabling branch control of subsequent input data.
A NOR gate 4 receives from the control parts 5 and 6 the signals 5b and 6b for indicating that the paths are empty and activated, and supplying an AK signal to the data transmission path 1 and the identifier transmission path 2. Thus, data transmission from the control parts 5 and 6 to the data transmission paths 7 and 8 is authorized or inhibited while branching/transmission of data from the data transmission path 1 to the control part 5 and 6 is authorized or inhibited by the UK and UL signals from the data transmission paths 7 and 8 and the paths preceding the data transmission paths 7 and 8, depending on whether or not the preceding transmission paths are empty.
The identifier transmission path 2 supplies an identifier decoding part 3 with an identifier, which indicates that the data received on the data transmission path 1 is to be transmitted to the data transmission path 7, for example. The identifier decoding part 3 decodes the identifier received from the identifier transmission path 2 and supplies a control signal 5c to the control part 5 for activating the transmission path. Thus, the data received from the data transmission path 1 can be transmitted to the data transmission path 7 through the control part 5. When the identifier transmission path 2 supplies the decoding part 3 with an identifier for indicating that the data is to be transmitted to the data transmission path 8, on the other hand, the identifier decoding part 3 supplies a control signal 6c to the control part 6 for activating the transmission path. Thus, the data received on the data transmission path 1 can be transmitted to the data transmission path 8 through the control part 6.
Within the data transmission paths 7 and 8 and the transmission paths preceding the data transmission paths 7 and 8, when the data transmission path 7 currently holds or transmits data, for example, the UK signal 5a is not supplied to the control part 5. Also when the transmission path preceding the data transmission path 7 currently holds or transmits data, the UL signal 5d is also not supplied to the control part 5. Thus, the control part 5 judges whether the data transmission path 7 or the transmission path preceding the data transmission path 7 is currently in transmission or in a busy condition for storing data inputted in a register (not shown) included in a control part 10 while supplying a high-level signal to one input terminal of the NOR gate 4. Thus, the NOR gate 4 is closed so that the AK signal is not supplied to the data transmission path 1 and the identifier transmission path 2.
In other words, when any of the data transmission paths 7 and 8 and the transmission paths preceding the transmission paths 7 and 8 currently holds or transmits data while the control parts 5 and 6 hold data, data received on the data transmission path 1 is not inputted in the control parts 5 and 6 but the data is held in the data transmission path 1. When the data transmission path 7, the transmission path preceding the data transmission path 7, the data transmission path 8 or the transmission path preceding the data transmission path 8 completes data transmission to cause transition from a busy condition into an empty state, the control part 5 or 6 is activated. Thus, the data held in the data transmission path 1 can be autonomously branched again in accordance with the identifier.
In the distributed data processing environment, a plurality of data processing equipment must conventionally be interconnected by providing each processing equipment with a plurality of data transmission units and associated input-output ports for different data groups to be processed. This conventional arrangement makes the hardware extremely complicated in construction and bulky in size with an accompanying high cost.